The cause and effect relationship between ectopic endometrial cell growth and characteristic local inflammatory response is unknown but is probably of fundamental importance in endometriosis (E). We are proposing to investigate this relationship by studying the interaction of inflammatory macrophages and endometrial stromal cells both in experiments in vitro and in ectopic E implants. The proposed studies are based on our early observations documenting phenotypic and secretory differences in E peritoneal macrophages as compared to those of normal women (N). Since E peritoneal macrophages release increased levels of growth factor(s) and connective tissue component(s) (fibronectin), a similar potential exists for macrophages in ectopic E implants. As a simplified in vitro model for E, we will examine the steady-state mRNA expression and production and inflammation mediators/growth factors and connective tissue components by interacting monocytes and stromal cells. In a limited fashion, similar experiments will then be carried out by using N and E peritoneal macrophages in the place of monocytes. In the view that sex steroids have potential of influencing both endometrial stromal and inflammatory cells, effect of physiologic concentrations of estradiol and progesterone and pharmacologic concentrations of danazol in these interactions will be assessed. In addition, direct effects of recombinant mediators/growth factors on stromal cell proliferation will be investigated in fresh primary cultures of endometrial stromal cells, endometrial stromal cell lines, and immunohistologic procedures will be employed in identification and characterization of inflammatory macrophages and their spatial relationship to proliferating stromal cells in ectopic E implants. Similar techniques combined with in situ hybridization will then determine the pattern of expression/production of inflammation mediators or connective tissue components by in situ macrophages/stromal cells in various morphologically distinct E lesions. The completion of these studies will enhance our understanding of the role of cellular interactions in the possibly self- perpetuating cycle of E-implant proliferation and associated inflammatory reaction.